The use of ultra-hard constructions comprising a body formed from ultra-hard materials such as diamond, polycrystalline diamond (PCD), cubic boron nitride (cBN), polycrystalline cubic boron nitride (PcBN) are well known in the art. An example of such constructions may be found in the form of cutting elements comprising an ultra-hard component or body that is joined to a metallic component or substrate. In such cutting elements, the wear or cutting portion is formed from the ultra-hard component and the metallic portion is provided for the purpose of attaching the cutting element to a desired wear and/or cutting device. In such known constructions, the ultra-hard component may be formed from those ultra-hard materials described above that provide a high level of wear and/or abrasion resistance that is greater than that of the metallic component.
The use of PCD as an ultra-hard material for forming such constructions is well known in the art. PCD is formed by subjecting a volume of diamond grains to high-pressure/high-temperature (HPHT) conditions in the presence of a suitable catalyst material, such as a solvent catalyst metal selected from Group VIII of the Periodic table. Oftentimes, the source of the solvent catalyst material used to form PCD is the metallic substrate, wherein the solvent catalyst material is present as a constituent of the substrate that migrates therefrom and infiltrates into the adjacent diamond body during HPHT processing. The resulting construction is a PCD compact comprising the PCD body joined to the substrate.
Over the years, improvements have been made to the PCD body portion of such ultra-hard constructions in terms of providing enhanced properties of thermal stability, wear resistance and abrasion resistance, thereby extending the effective service life of such ultra-hard constructions to the point where other elements of the construction now operate to govern service life. For example, it has been discovered that the substrate component of such ultra-hard constructions, because they are subjected to extended service life by virtue of the improved PCD body, suffer erosion damage due to long exposure down hole when subjected to extended exposure to the drilling debris and the mud jets during a drilling operation. This erosion damage ultimately results in the failure of the ultra-hard construction, thereby effectively limiting service life.